textproduct: Albany

WHAT HAS CHANGED

SPC has continued the Slight Risk (level 2 of 5) for severe thunderstorms across the entire region Saturday afternoon into Saturday evening. While some uncertainty in the convective evolution remains, guidance has trended higher with the amount of instability expected tomorrow, at least for western areas. SPC has expanded the 5% tornado risk further east into our area.

KEY MESSAGES

1) Widespread showers and thunderstorms are expected tomorrow afternoon and evening. Some storms may be severe with damaging winds, locally heavy rain, and even an isolated tornado.

2) Additional showers and thunderstorms are expected Tuesday into Tuesday night. Again, some strong to severe storms may occur.

DISCUSSION

KEY MESSAGE 1... As of 2:40 PM EDT...It is a pleasant afternoon across the region, with relatively low humidity, temperatures in the 70s to low 80s, and Canadian wildfire smoke having mainly pushed off to the south of our region. Tranquil weather continues through most of tonight, although the plume of smoke to our south does look to lift back north overnight as a warm front approaches from the south. Increasing clouds tonight will keep temperatures a few degrees warmer than last night, and a few showers are possible towards sunrise.

Tomorrow looks like a potentially busy severe weather day. As a potent upper shortwave digs into the upper Great Lakes region, an associated sub 1000 mb sfc low will track through the St. Lawrence Valley to our north. The deepening low will lift a warm front north through the region late tonight/tomorrow morning, placing us in the warm sector tomorrow afternoon. A pre-frontal trough will likely result in some convection developing by late tomorrow morning, departing to the east by early to mid- afternoon. Then, the approaching cold front will result in another round of convection late tomorrow afternoon and evening across the region, which is when the best chance for severe weather will be. A few discrete cells are also possible behind the pre-frontal trough and ahead of the second line of storms.

Overall, guidance has trended more impressive with the amount of instability tomorrow, with decent agreement for areas west of I-87 seeing 1000-1500 J/kg of SBCAPE with 500-1000 J to the east per the 12z HREF. This will overlap with impressive low-level and deep-layer thanks to a 35-45 kt 850 mb LLJ and 45-50 kt westerlies at 500 mb. While deep-layer shear vectors have a fairly perpendicular component to the approaching front, strong forcing from the upper trough, right entrance of the upper jet, and strong low-level convergence along the cold front may result in any discrete cells growing upscale into a line or broken line relatively quickly. Main hazard will be damaging winds, but a couple of tornadoes are also possible given low (<1000 ft) LCLs, good low-level veering of the winds and curved hodographs, and 0-1 km SRH of around 200 m2/s2. Isolated instances of marginally severe hail can't be ruled out with any discrete supercells that develop ahead of the main cold front, but overall the threat looks low based on warm, moist profiles and mediocre mid-level lapse rates.

That said, there are still a few potential "failure modes" that could limit the severe potential tomorrow. First, the pre- frontal trough looks to come through early enough that the potential for it to result in severe weather looks rather low, but it may be late enough that the associated convection and/or lingering cloud cover prevent the atmosphere from fully recovering/destabilizing tomorrow afternoon ahead of the main cold front. The second potential limiting factor is if the wildfire smoke that will be overhead reduces the amount of daytime heating and thus the amount of instability. Finally, the convection ahead of the cold front likely arrives around the I-90 corridor towards sunset, so instability may be starting to wane at this point. All said, there is a lot of potential for severe weather tomorrow, but if ingredients don't all align perfectly then this could limit the coverage and intensity of severe weather. SPC has upgraded areas to our west to an enhanced risk where there will be more instability and more favorable timing of the cold frontal passage, but kept our entire area in a slight risk likely due to some of the aforementioned limiting factors. Highest chance for severe weather in our area looks to be for the southern ADKs, Mohawk Valley, and Catskills.

Finally, will mention the heavy rain threat tomorrow. WPC has a marginal risk ERO for most of our area, but clipper our southern couple counties with their slight risk. Heavy rain is certainly possible with PWATs expected to rise to 1.75-2" tomorrow and warm cloud depths of 10-12 kft. However, storm motions look relatively fast and most areas are going on 7-10 days since the last appreciable rainfall, so this should greatly reduce/limit the threat for flash flooding tomorrow. In fact, most of the rain that falls tomorrow will be quite beneficial. The only way we foresee much in the way of hydro issues is if we see multiple rounds of heavy rain tracking over the more urban areas, so we will message that for the ALY CWA the hydro threat is secondary to that for severe thunderstorms.

KEY MESSAGE 2...The cold front tracks through our region Saturday night, with showers and storms coming to and end relatively early in the overnight period. Sunday will be a cooler and less humid day with dry weather. Tranquil weather continues into Monday with continued comfortable humidity, but temperatures trend back up into the low 80s for valley areas. Active weather returns for the Tuesday, possibly into Wednesday timeframe. Guidance is in good agreement that an unusually deep upper trough or ULL (-2 to -3 STD DEV per the NAEFS) will be tracking into the Great Lakes region. An associated sfc low tracking to the N/NW of our region will drag an attendant a cold front through our area. Shear and forcing already look fairly impressive, so if the timing of the frontal passage lines up with peak diurnal heating then some strong to severe storms would certainly be possible. That said, details, including timing, remain uncertain this far out in time. SPC has the D5 slight risk equivalent area just to the west of our CWA, but this certainly bears watching over the coming days. Drier and cooler weather should return by the end of next week.

AVIATION /18Z FRIDAY THROUGH WEDNESDAY/

Through 18Z Saturday... The region is getting a small break from smoky/hazy conditions today, with VFR prevailing across all terminals to start off this TAF period. Light winds out of the west to northwest will persist through this evening, with some moderate gusts expected at KPSF. Winds will weaken after sunset, becoming light and variable at all terminals overnights, with only scattered high clouds overhead. The Canadian wildfire smoke will return overnight into Saturday morning as winds shift to out of the south, potentially lowering visibilities, but VFR conditions are expected to persist through the morning at this time. Showers are expected to develop on Saturday afternoon at the tail end of this period, with the potential for some thunderstorms at KPOU and KPSF in the last few hours of this TAF period. Isolated heavy downpours and storms could bring cigs and vis down to MVFR at KPOU and KPSF, reflected by the PROB30 groups.

Outlook...

Saturday Night: High Operational Impact. Definite SHRA...TSRA. Sunday: Low Operational Impact. Breezy. NO SIG WX. Sunday Night: No Operational Impact. NO SIG WX. Monday: No Operational Impact. NO SIG WX. Monday Night: No Operational Impact. NO SIG WX. Tuesday: High Operational Impact. Breezy. Likely SHRA...TSRA. Tuesday Night: High Operational Impact. Definite SHRA...TSRA. Wednesday: Moderate Operational Impact. Breezy. Chance of SHRA...TSRA.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...Air Quality Alert until midnight EDT tonight for NYZ038- 063>066. MA...None. VT...None.